Stockholders' Equity, Equity Incentive Plans and Warrants (Summary of Restricted Stock Awards Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Options outstanding, number of shares	9,850,498	8,952,129
Options outstanding, weighted average exercise price	$ 2.58	$ 2.93
Options granted (in shares)	2,331,500
Options granted, weighted average exercise price	$ 1.05	$ 0.89	$ 1.78
Options forfeited (in shares)	(268,985)
Restricted Stock [Member]
Options outstanding, number of shares		655,402
Options outstanding, weighted average exercise price	$ 1.73	$ 2.16
Options granted (in shares)	30,000
Options granted, weighted average exercise price	$ 1.74
Options vested (in shares)	(567,268)
Options vested, weighted average exercise price	$ 2.22
Options forfeited (in shares)	(25,323)
Options forfeited, weighted average exercise price	$ 1.84
Options outstanding and unvested (in shares)	92,811